Pen for use with a touch screen

ABSTRACT

A method includes transmitting, by a touch screen device, signals on electrodes. The method further includes detecting, by a pen, a signal of the signals via an electrode of the electrodes. The method further includes creating, by the pen, a representation of the signal and transmitting the representation of the signal in accordance with a pen recognition signal format. The method further includes detecting, by the touch screen device, a change in the electrical characteristic of the electrode that is caused by the representation of the signal. The method further includes determining, by the touch screen device, that the pen is causing the change to the electrical characteristic of the electrode based on the pen recognition signal format.

CROSS REFERENCE TO RELATED PATENTS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120, as a continuation-in-part of U.S. Utility patentapplication Ser. No. 16/436,698, entitled “PEN FOR USE WITH A TOUCHSCREEN,” filed Jun. 10, 2019, pending, which is hereby incorporatedherein by reference in its entirety and made part of the present U.S.Utility Patent Application for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates to computer systems and more particularly tointeraction with a touch screen of a computing device.

Description of Related Art

Computers include user interfaces to receive data from a user and tooutput data to a user. A common user interface is a graphical userinterface (GUI) that provides images, or icons, for various types ofdata input (e.g., select a file, edit a word, type a character, draw apicture, look at a photo, format a document, etc.). In an example, theuser selects an icon by manipulating a mouse to align a cursor with anicon and then “selects” the icon. In another example, the user selectsan icon by touching the screen with the user's finger or with a specialpen.

For general use of a pen with computers from different manufacturersand/or having different touch screen technologies, a pen includes aring-back topology as described in patent application PCT/US201267897.The ring-back topology includes an inverting charge integrator and aninverting amplifier. When the tip of a ring-back pen touches the screen,the tip receives a signal from the screen. The inverting chargeintegrator integrates and inverts the received signal. The invertingamplifier inverts the integrated and inverted signal to produce anoutput signal that resembles the received signal. The pen sends theoutput signal back to the screen. The output signal affects the signaltransmitted by the screen, which screen interprets as a touch.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a communicationdevice with a pen and/or an input device in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computingdevice in accordance with the present invention;

FIG. 3 is a schematic block diagram of another embodiment of a computingdevice in accordance with the present invention;

FIG. 4 is a schematic block diagram of an embodiment of a touch screenelectrode pattern in accordance with the present invention;

FIG. 5 is a schematic block diagram of an example of capacitance of atouch screen with no touch in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of capacitance of atouch screen with a touch from a pen or a device in accordance with thepresent invention;

FIG. 6A is a schematic block diagram of an embodiment of an operationalamplifier configuration in accordance with the present invention;

FIG. 7 is a schematic block diagram of an embodiment of a pen inaccordance with the present invention;

FIG. 8 is a schematic block diagram of another embodiment of a pen inaccordance with the present invention;

FIG. 9 is a schematic block diagram of an embodiment of asense-regulation circuit and a response circuit of a pen in accordancewith the present invention;

FIG. 10 is a schematic block diagram of an example of ring-back with nodata in accordance with the present invention;

FIG. 11 is a schematic block diagram of an example of ring-back withdata in accordance with the present invention;

FIG. 12 is a schematic block diagram of another embodiment of asense-regulation circuit and a response circuit of a pen in accordancewith the present invention;

FIG. 13 is a schematic block diagram of another embodiment of a pen inaccordance with the present invention;

FIG. 14 is a schematic block diagram of another embodiment of a pen inaccordance with the present invention;

FIG. 15 is a schematic block diagram of another embodiment of asense-regulation circuit of a pen in accordance with the presentinvention;

FIG. 16 is a schematic block diagram of another embodiment of asense-regulation circuit of a pen in accordance with the presentinvention;

FIG. 17 is a schematic block diagram of an embodiment of a data sourcecircuit and a processing circuit of a pen in accordance with the presentinvention;

FIG. 18 is a schematic block diagram of an embodiment of a data sensecircuit of a pen in accordance with the present invention;

FIG. 19A is a schematic block diagram of an embodiment of a device inaccordance with the present invention;

FIG. 19B is a schematic block diagram of another embodiment of a devicein accordance with the present invention;

FIG. 20 is a schematic block diagram of an embodiment of asense-regulation circuit of a device in accordance with the presentinvention;

FIG. 21 is a schematic block diagram of another embodiment of asense-regulation circuit of a device in accordance with the presentinvention;

FIG. 22 is a schematic block diagram of an embodiment of a touch screento touch screen communication between two computing devices inaccordance with the present invention;

FIG. 23A is a schematic block diagram of an example of a frequencypattern representing data in accordance with the present invention;

FIGS. 23B-23F are schematic block diagrams of examples of electrodepatterns representing data in accordance with the present invention;

FIG. 24 is a schematic block diagram of an example of a device includinga housing and AC coupling circuit in accordance with the presentinvention;

FIG. 25 is a schematic block diagram of an embodiment of a device inaccordance with the present invention;

FIG. 26 is a logic diagram of an example of a method for pen and touchscreen device interaction in accordance with the present invention;

FIG. 27 is a schematic block diagram of an example of a signal and a pengenerated representation of the signal in accordance with the presentinvention;

FIG. 28 is a schematic block diagram of another example of a signal anda pen generated representation of the signal in accordance with thepresent invention; and

FIG. 29 is a logic diagram of another example of a method for pen andtouch screen device interaction in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a computingdevice 10 having a touch screen 12, which may further include a displayto form a touch screen display. The computing device 10, which will bediscussed in greater detail with reference to one or more of FIGS. 2-3,may be a portable computing device and/or a fixed computing device. Aportable computing device may be a social networking device, a gamingdevice, a cell phone, a smart phone, a digital assistant, a digitalmusic player, a digital video player, a laptop computer, a handheldcomputer, a tablet, a video game controller, and/or any other portabledevice that includes a computing core.

A fixed computing device may be a computer (PC), an interactive whiteboard, an interactive table top, an interactive desktop, an interactivedisplay, a computer server, a cable set-top box, vending machine, anAutomated Teller Machine (ATM), an automobile, a satellite receiver, atelevision set, a printer, a fax machine, home entertainment equipment,a video game console, and/or any type of home or office computingequipment. An interactive display functions to provide users with aninteractive experience (e.g., touch the screen to obtain information, beentertained, etc.). For example, a store provides interactive displaysfor customers to find certain products, to obtain coupons, to entercontests, etc.

A pen 16 and/or a device 14 interacts with the touch screen 12 tocommunication data with the computing device 10. For example, the pen 16touches, or nearly touches, the touch screen at a pen interaction area20. Within the pen interaction area 20, the touch screen 12 transmits asignal, or multiple signals, which are received by the pen 16. In a ringback mode, the pen 16 mimics the signal it receives and sends it back tothe touch screen 12. In a more advanced mode, the pen 16 includes datawith the ring back signal to provide additional information to the touchscreen. For example, the data includes pen orientation data (e.g.,angles of the pen in two or more axis), pressure data (e.g., how hardthe user is pressing the pen on the screen), pen functionality (e.g.,fine tip, coarse tip, clean line, fuzzy line, etc.), pen mode (e.g.,draw, write, erase), pen features (e.g., color, button presses, etc.),pen data (e.g., battery life, user information, feature set,capabilities, etc.), etc.

In another advanced mode, the touch screen 12 provides additional datato the pen 16. For example, the signal, or signals, transmitted by thetouch screen include embedded data. The embedded data for the pen 16includes a variety of information. For example, the embedded data forthe pen includes feedback for fine tuning the interaction between thepen and the touch screen (e.g., frequency selection, power control,etc.). In another example, the embedded data for the pen includesauthentication data to ensure that user of the pen on the computingdevice is authorized to do so.

The device 14 interacts with the touch screen 12 in a similar manner asthe pen 16, but may include more touch points to provided additionalinformation. For example, the device 14 is a mouse, a ruler, a gamepiece, an educational piece for communicating data with an interactivedesktop, an interactive tabletop, and/or an interactive white board. Asanother example, the device 14 is a cell phone case for facilitatingcommunication between a cell phone and an interactive desktop, aninteractive tabletop, and/or an interactive white board. As yet anotherexample, the device 14 is circuitry included in cell phones to enabletouch screen to touch screen communication.

FIG. 2 is a schematic block diagram of an embodiment of a computingdevice 10 that includes a core control module 40, one or more processingmodules 42, one or more main memories 44, cache memory 46, a videographics processing module 48, a display 50, an Input-Output (I/O)peripheral control module 52, one or more input interface modules, oneor more output interface modules, one or more network interface modules60, and one or more memory interface modules 62. A processing module 42is described in greater detail at the end of the detailed description ofthe invention section and, in an alternative embodiment, has a directionconnection to the main memory 44. In an alternate embodiment, the corecontrol module 40 and the I/O and/or peripheral control module 52 areone module, such as a chipset, a quick path interconnect (QPI), and/oran ultra-path interconnect (UPI).

Each of the main memories 44 includes one or more Random Access Memory(RAM) integrated circuits, or chips. For example, a main memory 44includes four DDR4 (4^(th) generation of double data rate) RAM chips,each running at a rate of 2,400 MHz. In general, the main memory 44stores data and operational instructions most relevant for theprocessing module 42. For example, the core control module 40coordinates the transfer of data and/or operational instructions fromthe main memory 44 and the memory 64-66. The data and/or operationalinstructions retrieve from memory 64-66 are the data and/or operationalinstructions requested by the processing module or will most likely beneeded by the processing module. When the processing module is done withthe data and/or operational instructions in main memory, the corecontrol module 40 coordinates sending updated data to the memory 64-66for storage.

The memory 64-66 includes one or more hard drives, one or more solidstate memory chips, and/or one or more other large capacity storagedevices that, in comparison to cache memory and main memory devices,is/are relatively inexpensive with respect to cost per amount of datastored. The memory 64-66 is coupled to the core control module 40 viathe I/O and/or peripheral control module 52 and via one or more memoryinterface modules 62. In an embodiment, the I/O and/or peripheralcontrol module 52 includes one or more Peripheral Component Interface(PCI) buses to which peripheral components connect to the core controlmodule 40. A memory interface module 62 includes a software driver and ahardware connector for coupling a memory device to the I/O and/orperipheral control module 52. For example, a memory interface 62 is inaccordance with a Serial Advanced Technology Attachment (SATA) port.

The core control module 40 coordinates data communications between theprocessing module(s) 42 and a network, or networks, via the I/O and/orperipheral control module 52, the network interface module(s) 60, and anetwork card 68 or 70. A network card 68 or 70 includes a wirelesscommunication unit or a wired communication unit. A wirelesscommunication unit includes a wireless local area network (WLAN)communication device, a cellular communication device, a Bluetoothdevice, and/or a ZigBee communication device. A wired communication unitincludes a Gigabit LAN connection, a Firewire connection, and/or aproprietary computer wired connection. A network interface module 60includes a software driver and a hardware connector for coupling thenetwork card to the I/O and/or peripheral control module 52. Forexample, the network interface module 60 is in accordance with one ormore versions of IEEE 802.11, cellular telephone protocols, 10/100/1000Gigabit LAN protocols, etc.

The core control module 40 coordinates data communications between theprocessing module(s) 42 and input device(s) via the input interfacemodule(s) and the I/O and/or peripheral control module 52. An inputdevice includes a keypad, a keyboard, control switches, a touchpad, amicrophone, a camera, etc. An input interface module includes a softwaredriver and a hardware connector for coupling an input device to the I/Oand/or peripheral control module 52. In an embodiment, an inputinterface module is in accordance with one or more Universal Serial Bus(USB) protocols.

The core control module 40 coordinates data communications between theprocessing module(s) 42 and output device(s) via the output interfacemodule(s) and the I/O and/or peripheral control module 52. An outputdevice includes a speaker, etc. An output interface module includes asoftware driver and a hardware connector for coupling an output deviceto the I/O and/or peripheral control module 52. In an embodiment, anoutput interface module is in accordance with one or more audio codecprotocols.

The processing module 42 communicates directly with a video graphicsprocessing module 48 to display data on the display 50. The display 50includes an LED (light emitting diode) display, an LCD (liquid crystaldisplay), and/or other type of display technology. The display has aresolution, an aspect ratio, and other features that affect the qualityof the display. The video graphics processing module 48 receives datafrom the processing module 42, processes the data to produce rendereddata in accordance with the characteristics of the display, and providesthe rendered data to the display 50.

The display 50 includes the touch screen 12, a plurality of drive-sensecircuits (DSC), and a touch screen processing module 82. The touchscreen 12 includes a plurality of sensors (e.g., electrodes, capacitorsensing cells, capacitor sensors, inductive sensor, etc.) to detect aproximal touch of the screen. For example, when a pen touches thescreen, capacitance of sensors proximal to the touch(es) are affected(e.g., impedance changes). As another example, when a pen touches thescreen, a sensor's signal is changed (e.g., magnitude increase,magnitude decrease, phase shift, etc.). The drive-sense circuits (DSC)coupled to the affected sensors detect the change and provide arepresentation of the change to the touch screen processing module 82,which may be a separate processing module or integrated into theprocessing module 42.

The touch screen processing module 82 processes the representativesignals from the drive-sense circuits (DSC) to determine the location ofthe touch(es). This information is inputted to the processing module 42for processing as an input. For example, a touch represents a selectionof a button on screen, a scroll function, a zoom in-out function, etc.

FIG. 3 is a schematic block diagram of another embodiment of a computingdevice 10 that includes the touch screen 12, the drive-sense circuits(DSC), the touch screen processing module 81, a display 83, electrodes85, the processing module 42, the video graphics processing module 48,and a display interface. The display 83 may be a large screen display(e.g., for portable computing devices) or a large screen display (e.g.,for fixed computing devices). In general, a large screen display has aresolution equal to or greater than full high-definition (HD), an aspectratio of a set of aspect ratios, and a screen size equal to or greaterthan thirty-two inches. The following table lists various combinationsof resolution, aspect ratio, and screen size for the display 83, butit's not an exhaustive list.

Width Height pixel screen screen size Resolution (lines) (lines) aspectratio aspect ratio (inches) HD (high 1280 720 1:1 16:9 32, 40, 43, 50,definition) 55, 60, 65, 70, 75, &/or >80 Full HD 1920 1080 1:1 16:9 32,40, 43, 50, 55, 60, 65, 70, 75, &/or >80 HD 960 720 4:3 16:9 32, 40, 43,50, 55, 60, 65, 70, 75, &/or >80 HD 1440 1080 4:3 16:9 32, 40, 43, 50,55, 60, 65, 70, 75, &/or >80 HD 1280 1080 3:2 16:9 32, 40, 43, 50, 55,60, 65, 70, 75, &/or >80 QHD (quad 2560 1440 1:1 16:9 32, 40, 43, 50,HD) 55, 60, 65, 70, 75, &/or >80 UHD (Ultra 3840 2160 1:1 16:9 32, 40,43, 50, HD) or 4K 55, 60, 65, 70, 75, &/or >80 8K 7680 4320 1:1 16:9 32,40, 43, 50, 55, 60, 65, 70, 75, &/or >80 HD and 1280->=7680  720->=43201:1, 2:3,  2:3 50, 55, 60, 65, above etc. 70, 75, &/or >80

The display 83 is one of a variety of types of displays that is operableto render frames of data into visible images. For example, the displayis one or more of: a light emitting diode (LED) display, anelectroluminescent display (ELD), a plasma display panel (PDP), a liquidcrystal display (LCD), an LCD high performance addressing (HPA) display,an LCD thin film transistor (TFT) display, an organic light emittingdiode (OLED) display, a digital light processing (DLP) display, asurface conductive electron emitter (SED) display, a field emissiondisplay (FED), a laser TV display, a carbon nanotubes display, a quantumdot display, an interferometric modulator display (IMOD), and a digitalmicroshutter display (DMS). The display is active in a full display modeor a multiplexed display mode (i.e., only part of the display is activeat a time).

The touch screen 12 includes integrated electrodes 85 that provide thesensors for the touch sense part of the touch screen display. Theelectrodes 85 are distributed throughout the display area or where touchscreen functionality is desired. For example, a first group of theelectrodes are arranged in rows and a second group of electrodes arearranged in columns.

The electrodes 85 are comprised of a transparent conductive material andare in-cell or on-cell with respect to layers of the display. Forexample, a conductive trace is placed in-cell or on-cell of a layer ofthe touch screen display. The transparent conductive material, which issubstantially transparent and has negligible effect on video quality ofthe display with respect to the human eye. For instance, an electrode isconstructed from one or more of: Indium Tin Oxide, Graphene, CarbonNanotubes, Thin Metal Films, Silver Nanowires Hybrid Materials,Aluminum-doped Zinc Oxide (AZO), Amorphous Indium-Zinc Oxide,Gallium-doped Zinc Oxide (GZO), and poly polystyrene sulfonate (PEDOT).

In an example of operation, the processing module 42 is executing anoperating system application 89 and one or more user applications 91.The user applications 91 includes, but is not limited to, a videoplayback application, a spreadsheet application, a word processingapplication, a computer aided drawing application, a photo displayapplication, an image processing application, a database application,etc. While executing an application 91, the processing module generatesdata for display (e.g., video data, image data, text data, etc.). Theprocessing module 42 sends the data to the video graphics processingmodule 48, which converts the data into frames of video 87.

The video graphics processing module 48 sends the frames of video 87(e.g., frames of a video file, refresh rate for a word processingdocument, a series of images, etc.) to the display interface 93. Thedisplay interface 93 provides the frames of video to the display 83,which renders the frames of video into visible images.

While the display 83 is rendering the frames of video into visibleimages, the drive-sense circuits (DSC) provide sensor signals to theelectrodes 85. When the screen is touched by a pen or device, signals onthe electrodes 85 proximal to the touch (i.e., directly or close by) arechanged. The DSCs detect the change for effected electrodes and providethe detected change to the touch screen processing module 81.

The touch screen processing module 81 processes the change of theeffected electrodes to determine one or more specific locations of touchand provides this information to the processing module 42. Processingmodule 42 processes the one or more specific locations of touch todetermine if an operation of the application is to be altered. Forexample, the touch is indicative of a pause command, a fast forwardcommand, a reverse command, an increase volume command, a decreasevolume command, a stop command, a select command, a delete command, etc.

If the signals received from the pen or device include embedded data,the touch screen processing module 81 interprets the embedded data andprovides the resulting information to the processing module 42. If,computing device 10 is not equipped to process embedded data, the pen ordevice still communicated with the computing device using the change tothe signals on the effected electrodes (e.g., increase magnitude,decrease magnitude, phase shift, etc.).

FIG. 4 is a schematic block diagram of an embodiment of a touch screenelectrode pattern that includes rows of electrodes 85-r and columns ofelectrodes 85-c. Each row of electrodes 85-r and each column ofelectrodes 85-c includes a plurality of individual conductive cells(e.g., white squares for rows, gray squares for columns) that areelectrically coupled together. The size of a cell depends on the desiredresolution of touch sensing. For example, a cell size is 5 millimetersby 5 millimeters, which provides adequate touch sensing for cell phonesand tablets. Making the cells smaller improves touch resolution and willtypically reduce touch sensor errors (e.g., touching a “w” by an “e” isdisplayed). While the cells are shown to be square, they may be of anypolygonal shape or circular shape.

The cells for the rows and columns may be on the same layer, as shown,or on different layers. The electrically coupling between the cells isdone using vias and running traces on another layer. Note that the cellsare on one or more ITO layers of a touch screen, which includes a touchscreen display.

FIG. 5 is a cross section schematic block diagram of an example ofcapacitance of a touch screen 12 with no touch of a pen or a device. Theelectrode 85 s are positioned proximal to dielectric layer 73, which isbetween cover dielectric layer 71 and the display substrate 75. Eachelectrode 85 has a self-capacitance, which corresponds to a parasiticcapacitance created by the electrode with respect to other conductors inthe display (e.g., ground, conductive layer(s), and/or one or more otherelectrodes). For example, row electrode 85-r has a parasitic capacitanceC_(p2) and column electrode 85-c has a parasitic capacitance C_(p1).Note that each electrode includes a resistance component and, as such,produces a distributed R-C circuit. The longer the electrode, thegreater the impedance of the distributed R-C circuit. For simplicity ofillustration the distributed R-C circuit of an electrode will berepresented as a single parasitic capacitance.

As shown, the touch screen 12 includes a plurality of layers 71-75. Eachillustrated layer may itself include one or more layers. For example,dielectric layer 71 includes a surface protective film, a glassprotective film, and/or one or more pressure sensitive adhesive (PSA)layers. As another example, the second dielectric layer 73 includes aglass cover, a polyester (PET) film, a support plate (glass or plastic)to support, or embed, one or more of the electrodes 85-c and 85-r, abase plate (glass, plastic, or PET), an ITO layer, and one or more PSAlayers. As yet another example, the display substrate 75 includes one ormore LCD layers, a back-light layer, one or more reflector layers, oneor more polarizing layers, and/or one or more PSA layers.

A mutual capacitance (Cm_0) exists between a row electrode and a columnelectrode. When no touch is present, the self-capacitances and mutualcapacitances of the touch screen 12 are at a nominal state. Depending onthe length, width, and thickness of the electrodes, separation from theelectrodes and other conductive surfaces, and dielectric properties ofthe layers, the self-capacitances and mutual capacitances can range froma few pico-Farads to 10's of nano-Farads.

FIG. 6 is a schematic block diagram of an example of capacitance of atouch screen with a touch from a pen 16 or a device 14. The pen 16 ordevice 14 is capacitive coupled to the row and column electrodesproximal to the touch. When the pen 16 or device 14 is touch by a personand is touching the touch screen, the person provides a path to groundsuch that the pen or device affects both the mutual capacitance and theself-capacitance. When the pen or device is not touched by a person,there is no path to ground and thus the pen or device only effects themutual capacitance.

In addition, the pen or device receives signals from the touch screenvia the capacitance coupling to the screen. The signals transmitted bythe pen or device to the touch screen are also through the capacitancecoupling and affect the signals on the electrodes 85.

As an example, the device 14 or pen 16 is capacitively coupled to thetouch screen of the computing device via capacitor Cx1 and/or capacitorCx2. For example, the pen 16 is coupled to the touch screen viacapacitor Cx1 or capacitor Cx2 and the device 14 is coupled to the touchscreen via capacitors Cx1 and Cx2. For a pen 16 touch, the capacitanceof Cx1 or Cx2 is about 50 femto-Farads. Depending on the area of thecontact surface of the device, the capacitance of Cx1 and/or Cx2 will bein the range of 50 femto-Farads to 10 or more pico-Farads.

Due to the small capacitance of Cx1 and/or Cx2, the pen 16 generates aneffective negative capacitance to enable the drive sense circuits (DSC)detect the presence of the pen. In an embodiment, the effective negativecapacitance is about −50 femto-Farads. To create the effective negativecapacitance, an operational amplifier configuration as shown in FIG. 6Amay be used.

FIG. 6A is a schematic block diagram of an embodiment of an operationalamplifier configuration 120 that includes an operational amplifier(op-amp), a capacitor (C), and a pair of resistors (R1 & R2). Theoperational amplifier configuration receives two inputs: a sense signal88 and a reference input 89. The sense signal 88, as described ingreater detail below, is received from one or more drive sense circuits(DSCs) of the touch screen display. The reference input 89 may be one ofa variety of inputs. In an example, the reference input 89 is a commonground. In another example, the reference input 89 is a reference signal(e.g., voltage or current). In a further example, the reference input 89is an analog representation of data to be transmitted to the touchscreen display. In this embodiment, the negative capacitance isapproximately equal to −C*R2/R1.

When the pen tip touches the screen, the operational amplifierconfiguration 120 creates Vo to be a scaled and inverted version of theVs. By varying the magnitude of Vo, the capacitive coupling between thepen and the touch screen can be varied. For example, by having Vs at 1volt and generating Vo to be 15 volts, capacitance Cx1 and/or Cx2 isincreased by about 16 times.

FIG. 7 is a schematic block diagram of an embodiment of a pen 16 thatincludes a first AC coupling circuit 80, a sense-regulation circuit 82,a response circuit 84, and a second AC coupling circuit 86. The touchscreen sensor array 100 includes row and column electrodes and drivesense circuits (DSC) driving and sensing each electrode.

The DSC drives a sensor drive signal 104 on to the electrode 85 toproduce a sense signal 88. The sensor drive signal 104 may be an analogsignal or a digital signal. In an embodiment, the sensor drive signal104 is an analog signal and the DSC functions as described in co-pendingpatent application entitled, “DRIVE SENSE CIRCUIT WITH DRIVE-SENSELINE”, having a serial number of Ser. No. 16/113,379, and a filing dateof Aug. 27, 2018. Note that, if the touch screen sensor array 100 doesnot include DSCs, then the touch screen functions in a ring-back mode(e.g., the pen's transmit signal 98 affects the sense signal 88, whichcan be detected by the touch screen sensor array as a touch of the penwith no extra data being communicated there between).

The first AC coupling circuit 80 is operable to receive a sense signal88 from the touch screen sensor array 100. The first AC coupling circuit80, which will be described in greater detail with reference to FIG. 8,provides the sense signal 88 to the sense-regulation circuit 82. Thesense-regulation circuit 82 is operable to compare the sense signal 88to a reference signal 90 (e.g., a voltage reference, a currentreference) to produce a comparison signal 92. As such, the comparisonsignal 92 is a representation of the sense signal 88 (e.g., invertedsignal, non-inverted signal, integrated signal, etc.).

The sense-regulation circuit 82 then generates a regulation signal 94based on the comparison signal 92 to regulate the receiving of the sensesignal 88. By regulating the receiving of the sense signal 88 (e.g.,keeping it a desired voltage level, a desired current level, etc.), theresulting comparison signal 92 is reflective of changes within thesense-regulation circuit 82 to keep the sense signal 88 at the desiredvoltage and/or current level with respect to the reference signal 90. Ifdata is embedded in the sense signal 88, the comparison signal 88 willinclude a representation of that data and a representation of the sensesignal 88. If there is not embedded data, the comparison signal 88 onlyincludes the representation of the sense signal 88.

The response circuit 84 is operable to generate a transmit signal 98based on the comparison signal 92 and data 96. In an embodiment, theresponse circuit 84 includes a processing circuit or processing moduleto combine the comparison signal 92 and the data 96. For example, theresponse circuit 84 modulates the data 96 on to the comparison signal 92to produce the transmit signal 98. As a specific example, the responsecircuit performs one or more of Amplitude Shift Keying (ASK), PhaseShift Keying (PSK), and Amplitude Modulation (AM) to produce thetransmit signal 98 from the comparison signal 92 and the data 96. In anembodiment, the response circuit is a signal generator as described inco-pending patent application entitled, “RECEIVE ANALOG TO DIGITALCIRCUIT OF A LOW VOLTAGE DRIVE CIRCUIT DATA COMMUNICATION SYSTEM”,having a serial number of Ser. No. 16/266,953, and a filing date of Feb.4, 2019.

The second AC coupling circuit 86 is operable to transmit the transmitsignal 98 to the touch screen sensor array 100. For example, the secondAC coupling circuit 86 sends the transmit signal to the electrode 85 viathe capacitive coupling. The DSC circuit senses the transmit signal 98on the electrode as a change in the sensor drive signal 104, where thechange is an impedance change, a voltage change, a current change, aphase change, a frequency change, and/or a magnitude change. The DSCprovides the detected change to the touch screen processing module 81(of FIG. 3), which processes the signal to determine a touch of the penand to further interpret the data contained in the transmit signal.

In an embodiment, there is no data 96. As such, the transmit signal 98includes the comparison signal 92, which is a representation of thesense signal 88. As such, the pen 16 is provided a regulated ring-backsignal to the touch screen. In another embodiment, the transmit signal98 includes the comparison signal 92 and the data 96, but the touchscreen sensor array 100 does not include DSCs. In this embodiment, thedata 96 embedded in the transmit signal 98 is ignored by the touchscreen sensor array 100 and the touch screen sensor array 100 processesthe comparison signal 92 contained in the transmit signal 98.

FIG. 8 is a schematic block diagram of another embodiment of a pen 16that includes a battery 110, one or more data source circuits 115,circuitry 112, a conductive pen tip 114, and a conductive pen shell &cone 116. The conductive pen tip 114 is composed of one or moreconductive materials and is electrically isolated from the conductiveshell & cone 116, which is also composed on one or more conductivematerials (e.g., metal traces in a plastic substrate, metal, ITO, aconductive polymer, etc.). In addition, the conductive pen tip 114 is atleast partially physically contained within the cone part of theconductive pen shell & cone 116. In another embodiment, the conductivepen tip 114 is electrically coupled via a coupling circuit to theconductive shell & cone 114. For example, the coupling circuit is one ormore of a wire, a capacitor, and an inductor.

The circuitry 112, which will be described in greater detail withreference to FIG. 9, is coupled to the conductive pen tip 114 and to theconductive shell & cone 116. In one embodiment, the first AC couplingcircuit 80 is the conductive pen tip 114 and the second AC couplingcircuit 86 is the conductive pen shell and cone 116. In anotherembodiment, the first AC coupling circuit 80 is a conductive pen shelland cone 116 and the second AC coupling circuit 86 is the conductive pentip 114.

The data source circuit 115 provides the data 96 to the circuitry 112,which includes the sense-regulation circuit 82 and the response circuit84. In an embodiment, the data source circuit 115 is a pressure sensorcoupled to a conductive pen tip 114. The pressure sensor measurespressure on the conductive pen tip when the conductive pen tip is inphysical contact with the touch screen. The pressure sensor converts themeasured pressure into the data 96.

In another embodiment, the data source circuit 115 is an orientationsensor (e.g., accelerometer, gyroscope, axial capacitance sensor array,etc.) that is measures three-dimensional orientation of on the pen 16when the pen is in physical contact with the touch screen. Theorientation sensor then converts the measured three-dimensionalorientation into the data 96.

FIG. 9 is a schematic block diagram of an embodiment of the circuity 112of the pen 16 that includes the sense-regulation circuit 82 and theresponse circuit 84. The sense-regulation circuit 82 includes anoperational amplifier configuration 120 (which may be implemented asshown in FIG. 6A or in a different manner), a regulation circuit 122,and a dependent current source 124. The response circuit 84 includes aprocessing module 126 and a drive circuit 128. The processing module 126is configured to provide, or include, a digital to analog converter 130and a modulator 132.

In an example of operation, the operational amplifier 120 receives thesense signal 88 at its negative input and a reference signal 90 at itspositive input to generate the comparison signal 92. The regulationcircuit 122 generates a regulation signal 94 from the comparison signal92. The dependent supply source 124 (e.g., a dependent current source, adependent voltage supply, a bidirectional dependent current source, abidirectional dependent voltage supply, etc.) generates an adjustmentsignal 125 such that the voltages inputted in to the operationalamplifier 120 remain substantially equal, which provides the regulatingof receiving the sense signal.

As a specific example, the sense signal 88 is a sinusoidal signal havinga frequency in the range of tens of Kilo-Hertz to tens of Giga-Hertz andthe reference signal 90 is a DC signal (e.g., a DC voltage reference ora DC current reference). The output of the operational amplifier 120(i.e., the comparison signal 92) will correspond to the inversion of thesense signal 88 (e.g., an inverted sinusoidal signal). The regulationcircuit 122 (which may be a capacitor, resistor, wire, combination ofcapacitors and/or resistors, an integrator, etc.) and the dependentsupply source 124 provide the gain for the feedback loop of thesense-regulation circuit 82 to generate the regulation signal 94 so thatthe comparison signal 92 does not get clipped (e.g., its magnitude islimited by the power supply voltage).

As another specific example, the sense signal 88 is a digital pulsetrain having a clock rate in the range of tens of Kilo-Hertz to tens ofGiga-Hertz and the reference signal 90 is a DC signal. The output of theoperational amplifier 120 (i.e., the comparison signal 92) willcorrespond to the inversion of the sense signal 88 (e.g., an inverteddigital pulse train). The regulation circuit 122 and the dependentsupply source 124 provide the gain for the feedback loop of thesense-regulation circuit 82 to generate the regulation signal 94 so thatinformation in the digital pulse train is retained by the comparisonsignal 92.

Returning to the example of operation, the digital to analog converter130 converts the data 96 into an analog data 97. The modulator 132modulates the analog data 97 with the comparison signal 92 to produce ananalog outbound data signal 134. The drive circuit 128 (e.g., a driver,a unity gain amplifier, a voltage to current converter, a current tovoltage converter, etc.) creates the transmit signal 98 from the analogoutbound data signal 134. As an example, the transmit signal 98 is ahigher power version (e.g., more voltage and/or more current) of theanalog output data signal 134.

The modulator 132 can modulate the analog data 97 with the comparisonsignal 92 in a variety of ways. For example, the modulator 132 usesAmplitude Shift Keying (ASK) to modulate the analog data 97 with thecomparison signal 92, which is done at an “n” cycle by cycle basis ofthe comparison signal, wherein “n” is an integer equal to or greaterthan 1. As another example, the modulator 132 uses Phase Shift Keying(PSK) to modulate the analog data 97 with the comparison signal 92,which is done at the “n” cycle by cycle basis of the comparison signal.As yet another example, the modulator 132 uses a combination of ASK andPSK to modulate the analog data 97 with the comparison signal 92, whichis done at the “n” cycle by cycle basis of the comparison signal. As afurther example, the modulator 132 uses Amplitude Modulation (AM) tomodulate the analog data 97 with the comparison signal 92, which is doneat the clock rate of the data 96.

FIG. 10 is a schematic block diagram of an example of ring-backsignaling with no data (e.g., the data is a null set for ring-back onlytouch sensing operation). As shown, the sense signal 88 is a sinusoidalsignal having a frequency in the range of tens of Kilo-Hertz to tens ofGiga-Hertz and the reference signal 90 (not shown) is a DC signal. Thecomparison signal 92 is the inversion of the sense signal (e.g., aninverted sinusoidal signal), which may have the same or different peakto peak value as the sense signal (shown to be less than). The transmitsignal 98 is a higher power version of the comparison signal 92.

FIG. 11 is a schematic block diagram of an example of ring-back withdata 96 that is modulated with the comparison signal using ASK. Asshown, the sense signal 88 is a sinusoidal signal and the comparisonsignal 92 is an inversion of the sense signal. The data 96 is shown asfour bits, those being 1, 1, 0, 1. For this example of ASK, the 1's arerepresented as a first magnitude of the transmit signal and the 0's arerepresented as a second magnitude of the transmit signal 98, where thefirst magnitude is greater than the second magnitude.

FIG. 12 is a schematic block diagram of another embodiment of thecircuitry 112 of the pen 16 that includes a sense-regulation circuit82-1 and a response circuit 84-1. The sense-regulation circuit 82-1includes the operational amplifier configuration 120 (which may beimplemented as shown in FIG. 6A or in a different manner), an analog todigital converter 140, a digital to analog converter 142, and thedependent supply source 124. As used herein, a suffix of a referencenumber indicates that the referenced component is similar to alike-referenced component with a different suffix, where an overalloperation of the liked-reference number components is similar, but theliked-reference number components operate on different data, operate indifferent domains (e.g., analog or digital, time or frequency), and/orperform in a different manner to achieve a similarly desired result.

The operational amplifier 120 generates an analog comparison signal 92-1based on the sense signal 88 and the reference signal 90. The analog todigital converter 140 converts the analog comparison signal 92-la intothe comparison signal 92-1. The digital to analog converter 142 convertsthe comparison signal 92-1 into the regulation signal 94-1. Thedependent supply source 124 generates the adjustment signal 125 based onthe regulation signal.

The processing module 126 of the response circuit 84-1 digitallymodulates the data 96 with the digital comparison signal 92-1 to producea digital outbound data signal 134-1. The drive circuit 128 includes adigital to analog converter 144, which converts the digital outbounddata signal 134-1 into the transmit signal 98.

FIG. 13 is a schematic block diagram of another embodiment of a pen 16-1that includes a battery 110, one or more data source circuits 115,circuitry 150, a conductive pen tip 114, and a pen shell & cone 116-1(which may or may not be conductive). The circuitry 150, which will bedescribed in greater detail with reference to FIG. 14, is coupled to theconductive pen tip 114 for transmitting and receiving data from thetouch screen. The data source circuit 115 provides the data 96 to thecircuitry 150, which includes a sense-regulation circuit 82-2.

FIG. 14 is a schematic block diagram of another embodiment of thecircuitry 150 of the pen 16-1. The circuitry 150 includes a processingcircuit 150 and the sense-regulation circuit 82-2.

In an example of operation, the AC coupling circuit 80-1 receives thesense signal 88 from the touch screen sensor array 100. In oneembodiment, the AC coupling circuit 80-1 is the conductive pen tip 114.In another embodiment, the AC coupling circuit 80-1 is the conductivepen shell and cone 116.

The sense-regulation circuit 82-2 receives the sense signal 88 andreceives a representation 160 of the data 96 from the processing circuit152. The processing circuit 152 will be described in greater detail withreference to FIG. 17. The sense-regulation circuit 82-2 generates acomparison signal 92-2 based on the sense signal 88 and therepresentation 160 of the data 96. The sense-regulation circuit 82-2then generates a regulation signal 94-2 to regulate receiving of thesense signal and transmitting of a transmit signal 98-1. The AC couplingcircuit transmits the transmit signal 98-1 to the touch screen.

In another embodiment, the sense-regulation circuit 82-2 generates aseparate ring back signal based on the sensed signal. A second ACcoupling circuit 86 of the pen 16-1 transmits the ring-back signal tothe touch screen.

FIG. 15 is a schematic block diagram of another embodiment of thesense-regulation circuit 82-2 of the pen 16-1. The sense-regulationcircuit 82 includes the operational amplifier configuration 120 (whichmay be implemented as shown in FIG. 6A or in a different manner), theregulation circuit 122, and the dependent current source 124.

In an example of operation, the operational amplifier 120 receives thesense signal 88 at its negative input and the representation 160 of thedata 96 at its positive input to generate the comparison signal 92-2.The regulation circuit 122 generates a regulation signal 94-2 from thecomparison signal 92-2. The dependent supply source 124 generates anadjustment signal 125-2 such that the voltages inputted into theoperational amplifier 120 remain substantially equal, which provides theregulating of receiving the sense signal 88 and regulation oftransmitting the transmit signal 98.

As a specific example, the sense signal 88 is a sinusoidal signal havinga frequency in the range of tens of Kilo-Hertz to tens of Giga-Hertz andthe representation 160 of the data 96 is a second sinusoidal signalhaving a different frequency than that of the sense signal. The outputof the operational amplifier 120 (i.e., the comparison signal 92)correspond to a difference between the sense signal 88 and therepresentation 160 of the data 96. The regulation circuit 122 and thedependent supply source 124 provide the gain for the feedback loop ofthe sense-regulation circuit 82 to generate the regulation signal 94 sothat the comparison signal 92 does not get clipped. As such, thecomparison signal 92-2 includes a representation (e.g., includes thesame information but may be of a different magnitude, phase, or domain)of the sense signal 88 and of the representation 160 of the data 96.

FIG. 16 is a schematic block diagram of another embodiment of thesense-regulation circuit 82-2 a and a receive digital processing module161 of the pen 16-1. The sense-regulation circuit 82-2 a includes theoperational amplifier configuration 120 (which may be implemented asshown in FIG. 6A or in a different manner), the analog to digitalconverter 140, the digital to analog converter 142 and the dependentcurrent source 124.

In an example of operation, the operational amplifier 120 receives thesense signal 88 at its negative input and the representation 160 of thedata 96 at its positive input to generate analog comparison signal 92-2.The analog to digital converter 140 converts the analog comparisonsignal 92-2 into a digital comparison signal 92-2 a. The digital toanalog converter 142 converts the digital comparison signal 92-2 a intothe regulation signal 94-2 a. The dependent supply source 124 generatesan adjustment signal 125-2 a such that the voltages inputted into theoperational amplifier 120 remain substantially equal, which provides theregulating of receiving the sense signal 88 and regulation oftransmitting the transmit signal 98.

The receive digital processing module 161 receives the comparison signal92-2 a and extracts, therefrom, receive data. The receive data isregarding interoperation of the touch screen and the pen. For example,the receive data is feedback from touch screen regarding data receivedfrom pen. As another example, the receive data is for calibration of thepen for use with the touch screen. As another example, the receive dataindicates a set of operations for the pen to use when interacting withthe touch screen.

FIG. 17 is a schematic block diagram of an embodiment of a data sourcecircuit 115 and a processing circuit 152 of a pen 16 and/or 16-1. Thedata source circuit 115 includes a sensing element 170 (e.g., atransducer, switch, circuit, combination, etc.) and a data sense circuit172. The processing circuit 152 includes a processing module 172 and adigital to analog converter 174.

In an example of operation, the sensing element sense a condition 176 ofthe pen. For example, the sensing element 170 senses pressure, tilt,color selection, erasure mode selection, other environmental condition,and/or other operational condition of the pen. The sensing element 170generates a condition signal 178 based on the sensed condition 176 ofthe pen. The data sense circuit 172 generates the data 96 based on thecondition signal 178 and a reference signal 180. The data sense circuit172 will be described in greater detail with reference to FIG. 18.

The processing module 172 generates digital outbound data 182 based onthe data 96. For example, the processing module 172 adjust formatting ofthe data 96 (e.g., non-return to zero, return to zero, Manchester,etc.), adjust data rate of the data 96, level shifting of the data, etc.The digital to analog converter 174 converts the digital outbound data182 into the representation 160 of the data 96.

FIG. 18 is a schematic block diagram of an embodiment of a data sensecircuit 172 that includes an operational amplifier configuration 120-2(which may be implemented as shown in FIG. 6A or in a different manner),a regulation circuit 122-2, and a dependent supply source 124-2. In anexample of operation, the operational amplifier 120-2 receives thecondition signal 178 at its negative input and a reference signal 180 atits positive input to generate the data 96.

The regulation circuit 122-2 generates a regulation signal 94-3 from thedata 96. The dependent supply source 124 (e.g., a dependent currentsource, a dependent voltage supply, a bidirectional dependent currentsource, a bidirectional dependent voltage supply, etc.) generates anadjustment signal 125-3 such that the voltages inputted in to theoperational amplifier 120-2 remain substantially equal, which providesthe regulating of receiving the sense signal.

As a specific example, the condition signal 178 is a non-sinusoidalsignal having a frequency in the range of tens of Kilo-Hertz to tens ofGiga-Hertz and the reference signal 180 is a DC signal (e.g., a DCvoltage reference or a DC current reference). The output of theoperational amplifier 120-2 (i.e., the data 96) will correspond to theinversion of the condition signal 178. The regulation circuit 122-2(which may be a capacitor, resistor, wire, combination of capacitorsand/or resistors, an integrator, etc.) and the dependent supply source124-2 provide the gain for the feedback loop of the data sense circuit172 to generate the regulation signal 94-3 so that the data 96 does notget clipped (e.g., its magnitude is limited by the power supplyvoltage).

FIG. 19A is a schematic block diagram of an embodiment of a device 14that includes a sense-regulation circuit 82-3, an AC coupling circuit200, an inbound data processing module 204, an outbound data processingmodule 206, and a processing module 203. The AC coupling circuit 200provides a communication path for the device 14 with the touch screensensor array 100 of the touch screen 12 of the computing device 10. Notethat the inbound data processing module 204, the outbound dataprocessing module 206, and the processing module 203 may be implementedin the same processing circuit, in different processing circuits, or acombination thereof.

For data communication from the computing device 10 to the device 14,the device receives a sense signal 88 via the AC coupling circuit 200.The sense-regulation circuit 82-3 processes the sense signal 88 in lightof a representation 210 of transmit data 208 (e.g., data from theprocessing module 203) to produce a receive error signal 212. As will bedescribed in greater detail with reference to FIGS. 20 and 21, thereceive error signal includes a combination of the comparison signal92-3 and the representation 210 of the transmit data 210.

The outbound data processing module 206 processes the receive errorsignal 212 and produces, therefrom, receive data 214. For example, theoutbound data processing module 214 includes a filtering circuit anddigital conversion circuit. The filtering circuit bandpass filters thereceive error signal 212 to substantially pass, unattenuated, thecomparison signal 92-3 (which is a representation of the sense signal88) and to attenuate other components of the receive error signal,including the representation 210 of the transmit data. For furtherexamples of an outbound data processing module 214 refer to co-pendingpatent application entitled, “ANALOG TO DIGITAL CONVERSION CIRCUIT WITHVERY NARROW BANDPASS DIGITAL FILTERING”, having a serial number of Ser.No. 16/365,169, and a filing date of Mar. 26, 2019.

The processing module 203 processes the receive data 214 to determine acommand, a data request, or other type of digital communication from thecomputing device 10. In addition, the processing module 203 generatestransmit data 208 for sending to the computing device 10.

The inbound data processing module 204 converts the transmit data 208into the representation 210 of the transmit data 208. The inbound dataprocessing module 204 may be implemented as a signal generator, which isdescribed in co-pending patent application entitled, “RECEIVE ANALOG TODIGITAL CIRCUIT OF A LOW VOLTAGE DRIVE CIRCUIT DATA COMMUNICATIONSYSTEM”, having a serial number of Ser. No. 16/266,953, and a filingdate of Feb. 4, 2019.

The sense-regulation circuit processes the representation 210 of thetransmit data 208 to produce a transmit signal 98-3. The AC couplingcircuit 200 sends the transmit signal 98-3 to the touch screen sensorarray 100.

FIG. 19B is a schematic block diagram of an embodiment of a device 14that includes a sense-regulation circuit 82-3, an AC coupling circuit200, an inbound data processing module 204, an outbound data processingmodule 206, and a communication circuit 202. The AC coupling circuit 200provides a communication path for the device 14 with the touch screensensor array 100 of the touch screen 12 of the computing device 10. Thecommunication circuit 202 provides a communication path with anothercomputing device 215. In an embodiment, the device 14 functions as afull duplex communication medium between the touch screen of thecomputing device 10 and a communication port of the other computingdevice 215.

For data communication from the computing device 10 to the othercomputing device 215, the device receives a sense signal 88 via the ACcoupling circuit 200. The sense-regulation circuit 82-3 processes thesense signal 88 in light of a representation 210 of transmit data 208(e.g., data from the other computing device 215 to the computing device10) to produce a receive error signal 212. As will described in greaterdetail with reference to FIGS. 20 and 21, the receive error signalincludes a combination of the comparison signal 92-3 and therepresentation 210 of the transmit data 210.

The outbound data processing module 206 processes the receive errorsignal 212 and produces, therefrom, receive data 214. For example, theoutbound data processing module 214 includes a filtering circuit anddigital conversion circuit. The filtering circuit bandpass filters thereceive error signal 212 to substantially pass, unattenuated, thecomparison signal 92-3 (which is a representation of the sense signal88) and to attenuate other components of the receive error signal,including the representation 210 of the transmit data. For furtherexamples of an outbound data processing module 214 refer to co-pendingpatent application entitled, “ANALOG TO DIGITAL CONVERSION CIRCUIT WITHVERY NARROW BANDPASS DIGITAL FILTERING”, having a serial number of Ser.No. 16/365,169, and a filing date of Mar. 26, 2019.

The communication circuit 202, which may be a USB (Universal Serial Bus)interface, a Lighting interface, a serial interface such as I3C/I2C, NFC(Near Field Communication), Bluetooth, Wi-Fi, etc., sends the receivedata 214 to the other computing device 215. In addition, thecommunication circuit 202 receives transmit data 208 from the othercomputing device 215 and provides it to the inbound data processingmodule 204.

The inbound data processing module 204 converts the transmit data 208into the representation 210 of the transmit data 208. The inbound dataprocessing module 204 may be implemented as a signal generator, which isdescribed in co-pending patent application entitled, “RECEIVE ANALOG TODIGITAL CIRCUIT OF A LOW VOLTAGE DRIVE CIRCUIT DATA COMMUNICATIONSYSTEM”, having a serial number of Ser. No. 16/266,953, and a filingdate of Feb. 4, 2019.

The transmit data 208 includes data regarding the other computing deviceand/or regarding the device, such as:

-   -   identification of the computing device (e.g., serial number, IP        address, cell phone number, user information, etc.);    -   identification of a type of computing device (e.g., cell phone,        mouse, keyboard, ruler, laptop, etc.);    -   location information regarding the computing device with respect        to the touch screen;    -   time synchronization information;    -   application activation information; and    -   request for touch screen to provide graphical user interface for        the computing device.

The sense-regulation circuit processes the representation 210 of thetransmit data 208 to produce a transmit signal 98-3. The AC couplingcircuit 200 sends the transmit signal 98-3 to the touch screen sensorarray 100.

FIG. 20 is a schematic block diagram of an embodiment of asense-regulation circuit 82-3 of a device 14. The sense-regulationcircuit 82-3 includes an operational amplifier 120-3, a regulationcircuit 122-3, and the dependent current source 124-3.

In an example of operation, the operational amplifier 120-3 receives thesense signal 88 at its negative input and the representation 210 of thetransmit data 208 at its positive input to generate the comparisonsignal 92-4. The regulation circuit 122-3 generates a regulation signal94-4 from the comparison signal 92-4. The dependent supply source 124-3generates an adjustment signal 125-4 such that the voltages inputtedinto the operational amplifier 120-3 remain substantially equal, whichprovides the regulating of receiving the sense signal 88 and regulationof transmitting the transmit signal 98-3.

As a specific example, the sense signal 88 is a sinusoidal signal havinga frequency in the range of tens of Kilo-Hertz to tens of Giga-Hertz andthe representation 210 of the transmit data 208 is a second sinusoidalsignal having a different frequency than that of the sense signal. Theoutput of the operational amplifier 120-3 (i.e., the comparison signal92-4) correspond to a difference between the sense signal 88 and therepresentation 210 of the transmit data 208. The regulation circuit122-3 and the dependent supply source 124-3 provide the gain for thefeedback loop of the sense-regulation circuit 82-3 to generate theregulation signal 94-4 so that the comparison signal 92-4 does not getclipped. As such, the comparison signal 92-4 includes a representation(e.g., includes the same information but may be of a differentmagnitude, phase, or domain) of the sense signal 88 and of therepresentation 210 of the transmit data 208.

FIG. 21 is a schematic block diagram of another embodiment of asense-regulation circuit 82-4 of a device 14. The sense-regulationcircuit 82-4 includes the operational amplifier configuration 120 (whichmay be implemented as shown in FIG. 6A or in a different manner), theregulation circuit 122, the dependent supply source 124, and a by-passline, which couples the representation 210 of the transmit data 208 to asecond AC coupling circuit 200-2. The operational amplifier 120, theregulation circuit 122, and the dependent supply source 124 function aspreviously described to generate the comparison signal 92-5 from thesense circuit 88 and a reference signal 212. In this embodiment, thereceive error signal 212 corresponds to the comparison signal 92-5.

FIG. 22 is a schematic block diagram of an embodiment of a touch screento touch screen communication between two computing devices 10 and 10-1.Both computing devices include a touch screen 12. When the computingdevices are face to face, the computing devices are able to communicatevia their respective touch screens.

To accomplish this, each computing device includes the circuitry ofdevice 14. The circuitry of device 14 may be integrated into the touchscreen control circuit or it may be a stand-alone circuit. When thecomputing devices are face to face, they can utilize a plurality ofpatterns (frequency and/or electrode enable) to communication data therebetween. One or more patterns may be used to set up the communicationand the patterns to be used for conveying data.

FIG. 23A is a schematic block diagram of an example of a frequencypattern representing data that is embedded in the sense signal and/ordata that is embedded in the transmit data. In this example, a frequencypattern is established over time to represent data. As shown, a firstfrequency corresponds to a logic value of 0 and a second frequencycorresponds to a logic value of 1. The pattern can be interpreted by theinbound and/or outbound processing modules to convert the pattern intodata and/or data into the pattern.

FIGS. 23B-23F are schematic block diagrams of examples of electrodepatterns representing data. FIG. 23B illustrates row electrodes 232 andcolumn electrodes 230 being in an orthogonal relationship. In theexamples of FIG. 23C through 23F, thicker lines for the electrodesindicate that the electrode is enable (e.g., a DSC is drive a sensingsignal on the electrode) and thinner lines for the electrodes indicatethat the electrode is not enable (e.g., a DSC is not drive a sensingsignal on the electrode).

FIG. 23C illustrates a row pattern where all column electrodes are notenabled and some of the row electrodes are enabled. The patterning ofwhich row electrodes to enable and disable for a data message may bedone in a bar code style. A pattern may be used to represent one bit ofdata, one byte of data, a specific message, or a specific command. As isreadily apparent, a large number of patterns can be obtained byselectively enabling and disabling row electrodes.

FIG. 23D illustrates a column pattern where all row electrodes are notenabled and some of the column electrodes are enabled to representdifferent data. FIG. 23E illustrates a row and a column pattern wheresome of the row electrodes are enabled and some of the column electrodesare enabled. FIG. 23F illustrates each row and column electroderepresenting a bit of data. In this example, there are 8 row electrodesand 8 column electrodes representing 16 bits of data. For the examplesof FIG. 23C through 23F, the row and column electrodes included in apattern area may encompass the entire touch screen area or a portionthereof.

FIG. 24 is a schematic block diagram of an example of a device includinga housing 222 and AC coupling circuit 200 of the device 14. In thisembodiment, the circuitry of the device is on the printed circuit board220, which is mounted in the housing 222. The housing 222 may beimplemented in a variety of ways. For example, the housing 222 is a casefor a phone. As another example, the housing is in the form of acomputing mouse. As yet another example, the housing is in the form of akeyboard.

The AC coupling circuit 200 is electrically coupled to the printedcircuit board 220 and includes a conductive pad that is electricallyisolated from the housing 22. The conductive pad may be implemented in avariety of ways. For example, the conductive pad is a pin. As anotherexample, the conductive pad is an electrode and/or metal trace. As yetanother example, the conductive pad is a conductive material having ashape to receive the sense signal from the touch screen and/or totransmit the transmit signal to the touch screen.

FIG. 25 is a schematic block diagram of an embodiment of a device 14-1that includes touch screen communication circuits 230-1 through 230-n, aprocessing module 232, and a communication circuit 202. Each of thetouch screen communication circuits includes at least one AC couplingcircuit that provides electrical connectivity to different drive sensecircuits (DSC 1-n) of the touch screen sensor array 100 of the touchscreen 12 of the computing device 10. The communication circuit 202provides a communication path with another computing device 215. In anembodiment, the device 14-1 functions as a full duplex communicationmedium between the touch screen of the computing device 10 and acommunication port of the other computing device 215.

The touch screen communication circuits 230-1 through 230-n may beimplemented in accordance with the circuitry of a pen and/or thecircuitry of a device as previously discussed. With multiple touchscreen communication circuits, multiple pieces of information can beconveyed between the computing devices 10 and 215. For example, thelocation and orientation of the device on the touch screen can bedetermined based on the information conveyed to the touch screen andwhich DSCs received the transmit signals. As another example, themultiple pieces of information can be used to determine motion of thedevice on the touch screen to indicate a gesture-based function or otherfunction.

FIG. 26 is a logic diagram of an example of a method regarding pen 14and touch screen device interaction. The touch screen device may beimplemented in a variety of ways. For example, the touch screen deviceis a computing device 10. As another example, the touch screen deviceincludes, with reference to FIG. 2, a processing module 42, main memory44, a touch screen 12 (which may or may not include a display), a touchscreen processing module 82, and a plurality of drive sense circuits(DSC).

The method begins at step 300, where the touch screen device transmitssignals on electrodes. In an embodiment, the electrodes are arranged ina grid of rows and columns as previously discussed. The signals includeself-capacitance detect signals and/or mutual capacitance detectsignals. For example, each of the self-capacitance detect signalsincludes a sinusoidal signal at a frequency (i.e., they are the samesignal transmitted on the electrodes by the DSCs). As another example,each of the mutual capacitance detect signals are a sinusoidal signalhaving different frequencies from each other and from theself-capacitance detect signals. The mutual capacitance detect signalsmay be transmitted on a subset of the electrodes or on all of theelectrodes depending on the desired touch screen sensing capabilities.

The method continues at step 302 where the pen detects one of thesignals on one of the electrodes. With reference to FIG. 8 and/or FIG.13, the pen receives the signal via capacitive coupling to the electrodevia the pen tip and/or the pen shell & cone.

Returning to FIG. 26, the method continues at step 304 where the pencreates a representation of the signal. For example, the pen comparesthe signal to a reference signal to produce a comparison signal. The penthen generates a regulation signal based on the comparison signal. Thepen further regulates the receiving of the sense signal based on theregulation signal. The pen further generates the representation of thesignal based on the comparison signal. Various embodiments of the penare described herein to generate the representation of the signal as atransmit signal.

The method continues at step 306 where the pen transmits therepresentation of the signal in accordance with a pen recognition signalformat. FIGS. 27 and 28 provide examples of the pen recognition signalformat, which will be subsequently described.

The method continues at step 308 where the touch screen device detects achange in an electrical characteristic of the electrode, where thechange is caused by the representation of the signal. For example, therepresentation of the signal changes capacitance of the electrode. Inparticular,

${C = {\frac{Q}{V} = \frac{Q}{Ed}}},$where C=Capacitance, V=voltage, Q=charge on the plates, E=electricfield, and d is the distance between the plates. As such, when therepresentation of the signal is proximal to the touch screen, it affectsthe charge on the plates (e.g., the electrode and ground forself-capacitance and the electrode and another electrode for mutualcapacitance). As a specific example, the representation of the signalincreases the charge on the electrode for self-capacitance therebyincreasing the self-capacitance of the electrode with respect to ground.As another specific example, the representation of the signal decreasesthe charge on the electrode for mutual-capacitance thereby decreasingthe mutual-capacitance of the electrode with respect to anotherelectrode. As another example, the representation of the signal changesthe electromagnetic field of the electrode, which changes its inductancefor inductance-based touch sensing.

The method continues at step 310 where the touch screen device detectsthat the pen is causing the change to the electrical characteristic ofthe electrode based on the pen recognition signal format. For example, afinger touch of the touch screen device causes the self-capacitance toincrease and the mutual capacitance to decrease in a similar manner asthe pen. The use of the pen recognition pattern allows the touch screendevice to readily determine that the change in self and/or mutualcapacitances is caused by a pen and not a finger.

FIG. 27 is a schematic block diagram of an example of a signal and a pengenerated representation of the signal in accordance with the penrecognition pattern. In this example, the pen creates the representationof the signal 322 as an inverted and scaled version of the signal 320(e.g., smaller or larger magnitude than the magnitude of the signal320). The pen transmits the representation of the signal in an on-offmanner. The rate of the on-off manner is greater than a rate at which ahuman finger can tap the touch screen device. For example, assume thatthe fastest rate a human can tap a screen is at 20 taps per second,which corresponds to one tap every 50 milliseconds. Thus, the pattern ofon-off is at the equivalent of 25 taps per second or greater.

After a predetermined period of time (e.g., 10 milliseconds or more),the on-off pattern for pen recognition ends and the pen transmits therepresentation of the signal in a continuous manner. The continuousmanner is used for conveying data from the pen to the touch screendevice and/or for conveying data from the touch screen device to thepen.

FIG. 28 is a schematic block diagram of another example of a signal anda pen generated representation of the signal in accordance with the penrecognition pattern. In this example, the signal 320 includes twofrequency components (e.g., sinusoidal signals at f1 and at f2). The penis operable to filter the signal to pass, substantially unattenuated,the first frequency component and to substantially attenuate the secondfrequency component to produce a filtered signal. The pen then createsthe representation of the signal based on the filtered signal andtransmits it.

The touch screen device detects that the representation of the signalincludes the first frequency component and not the second frequencycomponent. Based on this, the touch screen device determines that thepen is causing the change to the electrical characteristic of theelectrode based on the representation of the signal including the firstfrequency component and not the second frequency component.

FIG. 29 is a logic diagram of another example of a method for pen andtouch screen device interaction. The method includes step 330 where thepen detects a second signal of the signals via a second electrode of theelectrodes. The method continues at step 332 where the pen creates arepresentation of the second signal. The method continues at step 334where the pen transmits the representation of the second signal. Themethod continues at step 336 where the touch screen device detects achange in the second electrical characteristic of the second electrodethat is caused by the representation of the second signal. The methodcontinues at step 338 where the touch screen device detects movement ofthe pen based on the change to the electrical characteristic of theelectrode and the change to the second electrical characteristic of thesecond electrode.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, text, graphics, audio, etc. any of which may generally bereferred to as ‘data’).

As may be used herein, the terms “substantially” and “approximately”provide an industry-accepted tolerance for its corresponding term and/orrelativity between items. For some industries, an industry-acceptedtolerance is less than one percent and, for other industries, theindustry-accepted tolerance is 10 percent or more. Other examples ofindustry-accepted tolerance range from less than one percent to fiftypercent. Industry-accepted tolerances correspond to, but are not limitedto, component values, integrated circuit process variations, temperaturevariations, rise and fall times, thermal noise, dimensions, signalingerrors, dropped packets, temperatures, pressures, material compositions,and/or performance metrics. Within an industry, tolerance variances ofaccepted tolerances may be more or less than a percentage level (e.g.,dimension tolerance of less than +/−1%). Some relativity between itemsmay range from a difference of less than a percentage level to a fewpercent. Other relativity between items may range from a difference of afew percent to magnitude of differences.

As may also be used herein, the term(s) “configured to”, “operablycoupled to”, “coupled to”, and/or “coupling” includes direct couplingbetween items and/or indirect coupling between items via an interveningitem (e.g., an item includes, but is not limited to, a component, anelement, a circuit, and/or a module) where, for an example of indirectcoupling, the intervening item does not modify the information of asignal but may adjust its current level, voltage level, and/or powerlevel. As may further be used herein, inferred coupling (i.e., where oneelement is coupled to another element by inference) includes direct andindirect coupling between two items in the same manner as “coupled to”.

As may even further be used herein, the term “configured to”, “operableto”, “coupled to”, or “operably coupled to” indicates that an itemincludes one or more of power connections, input(s), output(s), etc., toperform, when activated, one or more its corresponding functions and mayfurther include inferred coupling to one or more other items. As maystill further be used herein, the term “associated with”, includesdirect and/or indirect coupling of separate items and/or one item beingembedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may be used herein, one or more claims may include, in a specificform of this generic form, the phrase “at least one of a, b, and c” orof this generic form “at least one of a, b, or c”, with more or lesselements than “a”, “b”, and “c”. In either phrasing, the phrases are tobe interpreted identically. In particular, “at least one of a, b, and c”is equivalent to “at least one of a, b, or c” and shall mean a, b,and/or c. As an example, it means: “a” only, “b” only, “c” only, “a” and“b”, “a” and “c”, “b” and “c”, and/or “a”, “b”, and “c”.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, “processing circuitry”, and/or “processing unit”may be a single processing device or a plurality of processing devices.Such a processing device may be a microprocessor, micro-controller,digital signal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, processing circuitry, and/or processing unitmay be, or further include, memory and/or an integrated memory element,which may be a single memory device, a plurality of memory devices,and/or embedded circuitry of another processing module, module,processing circuit, processing circuitry, and/or processing unit. Such amemory device may be a read-only memory, random access memory, volatilememory, non-volatile memory, static memory, dynamic memory, flashmemory, cache memory, and/or any device that stores digital information.Note that if the processing module, module, processing circuit,processing circuitry, and/or processing unit includes more than oneprocessing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,processing circuitry and/or processing unit implements one or more ofits functions via a state machine, analog circuitry, digital circuitry,and/or logic circuitry, the memory and/or memory element storing thecorresponding operational instructions may be embedded within, orexternal to, the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry. Still further notethat, the memory element may store, and the processing module, module,processing circuit, processing circuitry and/or processing unitexecutes, hard coded and/or operational instructions corresponding to atleast some of the steps and/or functions illustrated in one or more ofthe Figures. Such a memory device or memory element can be included inan article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with one or more other routines. In addition, a flow diagrammay include an “end” and/or “continue” indication. The “end” and/or“continue” indications reflect that the steps presented can end asdescribed and shown or optionally be incorporated in or otherwise usedin conjunction with one or more other routines. In this context, “start”indicates the beginning of the first step presented and may be precededby other activities not specifically shown. Further, the “continue”indication reflects that the steps presented may be performed multipletimes and/or may be succeeded by other activities not specificallyshown. Further, while a flow diagram indicates a particular ordering ofsteps, other orderings are likewise possible provided that theprinciples of causality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

While the transistors in the above described figure(s) is/are shown asfield effect transistors (FETs), as one of ordinary skill in the artwill appreciate, the transistors may be implemented using any type oftransistor structure including, but not limited to, bipolar, metal oxidesemiconductor field effect transistors (MOSFET), N-well transistors,P-well transistors, enhancement mode, depletion mode, and zero voltagethreshold (VT) transistors.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form asolid-state memory, a hard drive memory, cloud memory, thumb drive,server memory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method comprises: transmitting, by a touchscreen device, a plurality of signals on a plurality of electrodes;detecting, by a pen, a signal of the plurality of signals via anelectrode of the plurality of electrodes; creating, by the pen, arepresentation of the signal, wherein the creating the representation ofthe signal includes: comparing the signal to a reference signal toproduce a comparison signal; generating a regulation signal based on thecomparison signal; and regulating the receiving of the sense signalbased on the regulation signal; and generating the representation of thesignal based on the comparison signal; transmitting, by the pen, therepresentation of the signal in accordance with a pen recognition signalformat, wherein the representation of the signal affects an electricalcharacteristic of the electrode carrying the signal; detecting, by thetouch screen device, a change in the electrical characteristic of theelectrode that is caused by the representation of the signal; anddetermining, by the touch screen device, that the pen is causing thechange to the electrical characteristic of the electrode based on thepen recognition signal format.
 2. The method of claim 1 furthercomprises: creating, by the pen, the representation of the signal as aninverted and scaled version of the signal; and transmitting, by the pen,the representation of the signal in an on-off manner, wherein a rate ofthe on-off manner is greater than a rate at which a human finger can tapthe touch screen device, and wherein the pen recognition signal formatindicates a pattern for the on-off manner.
 3. The method of claim 2further comprises: transmitting, by the pen, the representation of thesignal in the on-off manner for a predetermined duration to enable thetouch screen device to identify the pen; and transmitting, by the pen,the representation of the signal in a continuous manner after expirationof the predetermined duration.
 4. The method of claim 1, wherein thedetecting the change in the electrical characteristic of the electrodecomprises: detecting, by the touch screen device, a change incapacitance of the electrode, wherein the electrical characteristicincludes a charge of the electrode, and wherein the representation ofthe signal changes the charge of the electrode to at least one of:increase self-capacitance of the electrode and decrease mutualcapacitance of the electrode with respect to another electrode.
 5. Themethod of claim 1, wherein the detecting the change in the electricalcharacteristic of the electrode comprises: detecting, by the touchscreen device, a change in inductance of the electrode, wherein theelectrical characteristic includes an electromagnetic field of theelectrode, and wherein the representation of the signal changes theelectromagnetic field of the electrode.
 6. The method of claim 1 furthercomprises: detecting, by the pen, a second signal of the plurality ofsignals via a second electrode of the plurality of electrodes; creating,by the pen, a representation of the second signal; transmitting, by thepen, the representation of the second signal, wherein the representationof the second signal effects a second electrical characteristic of thesecond electrode carrying the second signal; detecting, by the touchscreen device, a change in the second electrical characteristic of thesecond electrode that is caused by the representation of the secondsignal; and determining, by the touch screen device, movement of the penbased on the change to the electrical characteristic of the electrodeand the change to the second electrical characteristic of the secondelectrode.
 7. The method of claim 1 further comprises: detecting, by thepen, the signal, wherein the signal includes a first frequency componentand a second frequency component; filtering, by the pen, the signal topass, substantially unattenuated, the first frequency component and tosubstantially attenuate the second frequency component to produce afiltered signal; creating, by the pen, a representation of the signalbased on the filtered signal; transmitting, by the pen, therepresentation of the signal; detecting, by the touch screen device,that the representation of the signal includes the first frequencycomponent and not the second frequency component; and determining, bythe touch screen device, that the pen is causing the change to theelectrical characteristic of the electrode based on the representationof the signal includes the first frequency component and not the secondfrequency component.
 8. A pen for use with a touch screen device, thedigital pen comprises: an AC coupling circuit operable to receive asignal from the touch screen device; a sense-regulation circuit operableto: receive the signal from the AC coupling circuit; compare the signalto a reference signal to produce a comparison signal; generate aregulation signal based on the comparison signal; and regulate receivingof the sense signal based on the regulation signal; a response circuitoperable to generate a representation of the signal based on thecomparison signal and in accordance with a pen recognition signalformat; and wherein the AC coupling circuit is further operable totransmit the representation of the signal to the touch screen device. 9.The pen of claim 8 further comprises: the response circuit is furtheroperable to create the representation of the signal as an inverted andscaled version of the signal; and the AC coupling circuit is furtheroperable to transmit the representation of the signal in an on-offmanner, wherein a rate of the on-off manner is greater than a rate atwhich a human finger can tap the touch screen device, and wherein thepen recognition signal format indicates a pattern for the on-off manner.10. The pen of claim 8, wherein the AC coupling circuit is furtheroperable to: transmit the representation of the signal in the on-offmanner for a predetermined duration to enable the touch screen device toidentify the pen; and transmit the representation of the signal in acontinuous manner after expiration of the predetermined duration. 11.The pen of claim 8 further comprises: the sense-regulation circuit isfurther operable to: receive a second signal from the AC couplingcircuit; compare the second signal to the reference signal to produce asecond comparison signal; generate a second regulation signal based onthe second comparison signal; and regulate receiving of the secondsignal based on the second regulation signal; the response circuit isfurther operable to generate a representation of the second signal basedon the second comparison signal; and the AC coupling circuit is furtheroperable to transmit the representation of the second signal to thetouch screen device.
 12. The pen of claim 8 further comprises: theresponse circuit is further operable to: generate an initialrepresentation of the signal based on the comparison signal, wherein thesignal includes a first frequency component and a second frequencycomponent and wherein the representation of the signal includes a firstfrequency component representation and a second frequency componentrepresentation; and filter the representation of the signal to pass,substantially unattenuated, the first frequency component representationand to substantially attenuate the second frequency componentrepresentation to produce the representation of the signal.